Improving Current Distribution Model for EBWCD using Flux Loops in QUEST

During the early phase of tokamak plasma start-up prior to the formation of a closed magnetic surface, various plasma current profiles are expected to be observed. Especially, the noninductive current drive (CD) by the electron Bernstein wave (EBW) is likely to be the most dominant, and the current profile is expected to focus on a local area predicted by the theoretical model. In addition, the EBWCD direction could be affected by a horizontal magnetic field induced by a toroidal magnetic field coil and feed-through. The magnetic flux data cannot be fitted by using a previous model described by Yoshinaga23), and hence, this model needs improvement. Consequently, an improved model is introduced in this paper based on the theoretical prediction of EBWCD. This model can be applied to reproduce the complex plasma current profile accurately during the early phase of the tokamak plasma start-up.